Wireless user devices, such as cellular smartphones, may run software applications, such as video streaming applications, audio/video teleconferencing applications, etc., in which data may be sent and/or received by the wireless user devices via a wireless telecommunications network, such as a cellular network. Some software applications use variable bitrate (“VBR”) techniques, in which the data rate of data sent and/or received by the applications are increased or decreased. For example, at the application layer of a user device, an application may communicate with an application server via the Internet, in order to determine an end-to-end bandwidth and/or latency of application traffic that is sent between the user device and the application server, and may request adjustments to the data rate of uplink and/or downlink traffic based on the measured bandwidth and/or latency.